I agree with Paul. The Schema will act a a pseudo database, much like you experience in MSSQL. One thing that concerns me is your comment about the user adding and dropping a new db in mssql. This flexibility in Oracle is not as easy to achieve. You could drop the user that owns a schema and as a result drop (DELETE) the schema. the users can be given permission to create new user accounts (Schema) and script a initial configuration. but the management is way too loose for most DBAs.

In Oracle all Schemas for the DB Instance are held in the a single logical file. Logical because the DB could span multiple files depending on the size and resource configurations.

Don't mean to confuse the issue, but the management of Oracle is NOTHING like MSSQL. For better or for worse, it is what it is.

Doug